The present invention relates to an apparatus and method for spinning and winding continuous filament yarns of synthetic high polymer plastics.
In the production of multifilament polymeric yarns, it is conventional to extrude the melt through a spinneret to produce a plurality of downwardly advancing bundle of filaments, to gather the filaments into a yarn which continues to advance downwardly, and to then wind the advancing yarn into a cross wound package. Typically, a number of yarns are processed in a side by side relationship, and the yarns are wound onto respective bobbin tubes which are coaxially mounted on a common winding spindle.
An apparatus and method of the described type are known from DE 42 03 076 and corresponding U.S. Pat. No. 5,343,601. As disclosed in these patents, the yarns are removed from the spinning zone at a high take-off speed by means of a yarn delivery mechanism. The delivery mechanism consists of two godets, around which the yarns partly loop. A yarn tension is built up in the yarns above the godets and causes the yarns to be drawn. The tension at which the yarns are wound is lower than the tension built up for drawing purposes.
In the known apparatus and method, the yarn tension is reduced due to the fact that the delivery mechanism is driven at a circumferential speed which is greater than the yarn running speed. A yarn tension level which is low for winding is therefore set immediately after the yarn runs off the last godet. The yarns are guided to the individual winding stations of the winding device after running off the godet.
The above process entails a problem in that each yarn has a specific yarn tension which is dependent upon the yarn course. Because they are deflected to a greater or lesser degree after leaving the spinning zone, the yarns already have varying tensions upon entering the delivery mechanism. The yarns are brought closer to each other before running onto the delivery mechanism and then spread apart after leaving the latter in order to be guided to the respective winding position. This is especially true in spinning plants where a high number of yarns are simultaneously spun in parallel in the spinning zone, and it results in significant variations in yarn tension between the individual winding positions. These differences in yarn tension give rise at the winding positions to packages of widely differing quality.
Also known from the PCT patent application WO 96/09425 are a method and an apparatus in which two long godets permitting a parallel yarn course are disposed before the winding device. Godets of a length in excess of 120 cm consequently have to be used for spinning apparatus with eight and more yarns spun at the same time. In order to be able to feed the yarns, the godets are mounted only on one side in a projecting manner on a carrier. This means that long godets of this kind can only be used with an average yarn speed. When yarn speeds exceed 6,000 m/min. and the godet diameter is in the range from 100 to 150 mm, the godets have to be driven at speeds of up to 20,000 rpm, which entails considerable problems in terms of service life.
It is accordingly an object of the present invention to provide an apparatus and method for spinning and winding continuous multifilament yarns, wherein the yarns are wound with a preselectable yarn tension in each winding station and at a high yarn speed.